This invention relates to a central locking system for at least two closeable openings in the body of a motor vehicle, the system including a pressure source for selectively generating under pressure or over pressure, locking devices assigned to individual openings to be closed, a plurality of pneumatic control units each including a control element cooperating with a cooresponding locking device, each locking element moveable between two control positions, and said control units being connected to the source of under pressure or over pressure so as to move their control elements into one of the control positions depending on pressure level in the source.
A known central locking system of this kind includes a plurality of control units assigned to respective locking devices and being parallel connected to a common main conduit leading to the pressure source. If in such prior art locking systems the control elements are to be actuated which are located outside the field of vision of the operator of the motor vehicle, for example the control elements for the locks of storages or outer storing spaces on buses or for trunks of passenger cars, the corresponding locking devices after actuation of the central locking system must be checked whether the locking action actually took place. This check-out is necessary inasmuch for example a locking device associated with a sluggish control element may remain open.